Variable inductance



April 30, 9- I P. CROSLEY, JR 1,710,966

VARIABLE INDUCTANCE Original Filed Nov. 5, 1923 2 Sheets-Sheet 1 44 21Inventor 48 16 ZWW 49 I Ai' orngy.

April 30, 1929. P. CROSLEY. JR

VARIABLE INDUCTANCE Original Filed Nov. :5, 1923 2 Sheets-Sheet 2Patented Apr. 3t),

UNITED ,STA'IES PATENT OFFICE.

POWEL CRGSLEY, ER., OF CINCINNATI, OHIO.

VARIABLE INDUS'IANCE.

Application filed. November 3, 1?;23,

My invention relates to apparatus coupling electrical circuitsinductively, more especially ci cuits of low voltage, as in radioapparatus and the like.

The object ofmy invention is to provide a simple, compact andinexpensive de ice of this character, permitting the degree of couplingof the circuits to be varied through a wide range with infinite numberct adjust ments within the range ct adjustment, by very simplemanipulation without liability of derangement, so that the device isreadily installed and operated by relatively unskilled users. Otherobjects will. appear'in the course of the ensuing description.

I attain these objects by the device illustrated, for example, in theaccompany drawings, in which Figure 1 is a side elevation, with part ofthe panel mounting shown in section;

Fig. 2 is an inverted plan view of the same, with the part of the panelmounting in section;

Fig. 3 is a vertical cross-section on the plane of the line 3-3 of Fig.1, further illustrating the arrangement of the spring for maintainingthe adjustment of the device, the panel mounting being omitted;

Fig. 4 is a detail perspective view of the spring; I

Fig. 5 is a rear end elevation o the device; and

Fig. 6 is a vertical longitudinal section of amodified device embodyingmy invention.

7 As shown in Figs. 1 to 5, inclusive, a bracket 1 is formed ot heavysheet metal bent to form yokes 2 and 3 at the front and rear ends,respectively, at right angles to the main part 41-; each yoke having amiddle square opening 5. The front yoke 2 has its opposite ends in theform'o't ea 1 (3 projecting laterally past the main part l, and each earhas a tapped hole through it, receiving a screw 7. These screws 7 passhack th rough the panel 8, and have fiat heads sunk in the front of thepanel so that the knob 9, fixed on the trout one of the square shaft 10siiding snugly in the square openings 5, may come back closely againstthe front at the panel 8.

The rear yoke 3 has'similar ears 11 at its opposite ends each havingc/1p d hole Renewed October 5, 1&28.

wart 13 from which radiate a plurality arms 14 of the same thickness asthe hub part 13, which latter has a central opening registering with thesquare opening 5 of the rear yoke when the core 12 is seci red to thisyoke by screws 15 passed forwardly through holes in the hub part 13 andscrewed into the tapped holes in the respective ears 11 of the yoke 3.

The spring 16 formed from flat resilient sheet metal. with flat members17 inclining down later: lly from a middle ridge 18 and terminating inarrow depending flanges 19 which flank the main part 4 of the bracket 1and lie closely against the respective lateral edges thereof, while theridge 18'bears upward against the bottom of the square shaft 10 and thelower sides of the members 17 of the spring. adjacent to their junctionswith the thing-es bear along the respective upper corners of the edgesoi the main part 1 of the yoke, as clearly seen in Fig. 3.

The square shaft 10 extends back past. the core 12, through the centralopening thereof, and has its rear end reduced to form the cylindricalthreaded part 20 and a shoulder 21 therearoinnl, against which is awasher 22 around the part 20. The movable core 23 is similar to theabove described core 12, with a hub part 2-l: and radial arms 25 ofuniform thickness; this core having a. tapped. hole centrally or". itshub part 2-1 which receives the threaded end part 20 of the shaft 10 andthe core being screwed forward firmly against the w sher 22- and held inthat position by a nut 26 screwed on the part 20 with a lock washer 27between the nut. and the core 23. As shown, this rear movable core 23has its arms 25 shorter than the arms 14 of the front fixed core, inaccordance with the requirement for less space thereon than on the fixedcore. Diametrically opposite holes 28 in the hub part 24: of the rearn1ovable core 23 serve for passage of the termine of the conductorcarried by the core.

lhe trout fixed coil 29 has one terminal 30 leading); from the base ofone of the core arms l t and is passed spirally around its core 12 andacross the arms 1% thereof until its last turn passes through a smallhole 31 in the outer end partof one oi the arms 14%, preferably, shown,the arm at which the i is 'wi n begins a just mentioned; the part t t-.eil, from, this hole torming the other terminal 32 of this coil. Itwill be understood, however, as is well known, that this coil 29 may betapped at various points throughout its extent of winding, as at 33 inFig. 2, by leaving extensions 34 and 35 to lead to a suitable tapswitch, which, being well known, is not illustrated. Such tappingpreferably is made adjacent to the same arm 14 at which the windingbegins and ends as before mentioned.

' The rear movable coil 36 is similarly wound on its core 23, but theinner end part 37 preferably is connected to a terminal wire 37 inside asuitably insulated tube 38 through which the wires are carried acrossthe front of the hub part 24, permitting the terminal wire 37' to passrearwardly out of this tube 38 through one of the holes 28 in the core23; and the outer end part 39 of the coil 36, after passing through asmall hole 40 in the outer end part of the arm 25 at the base of whichthe winding starts, is con nected to a similar terminal wire 39 inside asimilar insulating tube 41, through which the wires lead across the hubpart, wit-h the terminal wire 39 passing out of the tube and backthrough the other hole 28 in the core 23. Preferably, these terminalwires 37' and 39' are more heavily insulated and more flexible than thewire of the coil 36, to withstand the handling required for connectionto apparatus with which the inductance is to be installed.

The square shaft 10, guided in the square openings 5 of the bracket 1,with the movable coil fixed against rotation, maintains the relativeangular positions of the coils, preventing mechanical injury to theterminal connections such as may occur with a round shaft which allowsthe operator to turn the knob 9 while adjusting the device. Theapparatus is illustrated and described as with the shaft 1() horizontal,but in some installations .it may be vertical, mounted on a horizontalpanel or the like, for up and down adjustment. In either case, thespring 16, with its parts 17 flexed apart and forcing the ridge part 18against the shaft 10 by their reaction against the edge parts of thebracket 1, and held from sidewise displacement by the flanges 19 atthese edge parts, will hold the movable coil in adjusted position, yetallow ready movement thereof by simply pulling or pushing on the knob 9.

In the example of Fig. 6, the square shaft is employed in conjunctionwith inductance coils of a different disposition. A tubular core 42 hasone end fixed to the upright panel 43 by small brackets 44. Centrally ofthis core a bearing bushing 45 has a part passed through an opening inthe panel 43 and a head against the front of the panel; the passedthrough part having threads receiving a nut 46 screwed against the rearside of thepanel, firmly fixing the bushing 45 therein. This bushing hasa square opening 47 receiving the square shaft 48 to slide snuglytherein, with the knob 48 on its front end in front of the panel 43, andhaving its rear end reduced forming the cylindrical threaded part 49 onwhich is screwed the movable core 50 in the form of a spool of greatdiameter relative to its axial length. This spool is firmly held by thenut 51 and lock washer 52 in a manner similar to the mounting of themovable core in the previous example.

This movable core 50 carries the movable inductance coil 53 woundtherearound, at a diameter such that this coil is carried very close tothe inner wall of the tubular fixed core 42, which wall is relativelythin, permitting close approach of the movable coil to the fixed coil 54wound on the exterior of the tubular core 42. A flat sprin 55 has oneend part emliracing the threaded rear projection of the bushing 45 andclamped against the rear of the panel 43 by the nut 46; the other endpart of the spring having a bend by which it resents a curved surfaceagainst the top 0 the square shaft 48. This modified device may bemounted horizontally as shown, or with the shaft 48 upright, for up anddown adjustment; in either case the spring 55 holding the movable coilin adjusted position, and the square shaft with the movable core orspool 50 fixed thereon preventing turning of the movable coil 53 andderangement of its exterior connections, as in the preceding example.

Other modifications may occur, in conjunction with differentinstallations, or to meet varying requirements, and therefore although Ihave rather specifically illustrated and described certain preferreddetails of construction of my invention. I do not wish to be understoodas being limited to such precise disclosure, but having thus fullydescribed my invention, what I claim as new and desire to secure byLetters Patent 1. In a device of the character described, thecombination with relatively movable coils, of a shaft of angularcross-section supporting one of the coils, means fixed to the other coiland having a bearing holding said shaft for non-rotative longitudinalsliding in said hearing, and having edges substantially parallel withsaid shaft, and a spring formed of a flat sheet bent with membersmeeting in a ridge bearing along said shaft and with flanges lying alongsaid edges of said bearing means.

2. In a device of the character described, the combination with twocoils, of a shaft of rectangular cross-section supporting one of thecoils, a bracket fixed to the other coil and having extensions spacedlongitudinally of the shaft, with rectangular openings in the extensionsholding the shaft for nonrotative longitudinal sliding in said bracket,the part of the bracket between said extensions having edgessubstantially parallel with said shaft, and a spring formed of a flatsheet bent with members meeting in a ridge bearing along said shaft andWith flanges lying along said edges of said part of said bracket.

In a device of the character described, a shaft of angularcross-section, a bracket comprising a main part extending along saidshaft and yokes at opposite ends of said main part each having anangular opening in which said shaft non-rotatively slides means forfixing one of said yokes to a support, a core fixed to the other yoke, acore fixed to said shaft beyond the first core, and coils wound on therespective cores.

4. In a device of the character described, a shaft of angularcross-section, a bracket comprising a main part extending along saidshaft and yokes at opposite ends of said main part each having anangular opening in which said shaft non-rotatively slides, means forfixing one of said yokes to a support, a core fixed to the other yoke, acore fixed to said shaft beyond the first core, each core comprising ahub part by means of which it is fixed to the yoke or sha t as the casemay be, and comprising arms radiating from said hub part, and coilswound on the respective cores from side to side of the arms thereof.

POVVEL CROSLEY, JR.

